CHEN90032 · Process Simulation and Control
The Complete Exam Bible · S1 2027Process Simulation and Control
CHEN90032 Process Simulation and Control is the University of Melbourne's graduate chemical-engineering subject on process dynamics and control — a 12.5-point subject in the Melbourne Master of Engineering (Chemical), graded on the University's WAM — where a mass or energy balance becomes a transfer function and that transfer function becomes a tuned, stable control loop. Taught in the Faculty of Engineering and IT, Process Simulation and Control runs in two halves — process dynamics (modelling, Laplace transforms, first- and second-order response) then process control (PID, stability, frequency response, tuning and multivariable control) — and is assessed on four continuous pieces plus a 60% closed-book final that is a hurdle. This exam-focused guide mirrors CHEN90032 as it is taught and examined at the University of Melbourne, with worked derivations, the tuning rules the exam supplies, and the sign, factor and unit traps that quietly cost marks.
What CHEN90032 covers
Twelve chapters take you from a process balance to a tuned, stable control loop -- the full CHEN90032 arc from process dynamics to multivariable control, mapped to the University of Melbourne teaching weeks.
How CHEN90032 is assessed
| Component | Weight | Format |
|---|---|---|
| Assignment 1 — Feedback control P&ID | 10% | Individual assignment (design feedback control scheme / P&ID); released ~Wk2, due ~Wk4 |
| Practical 1 — cooling-tower / distillation-column control | 10% | Individual lab report ~1000 words + exec summary (step-test → fit transfer functions → Simulink); ~Wk5 to ~Wk8 |
| Assignment 2 — TBD (control design/tuning) | 10% | Individual assignment; released ~Wk7, due ~Wk10 |
| Practical 2 — distillation-column control | 10% | Individual lab report; ~Wk9 to ~Wk12 |
| End-of-semester examination | 60% | Invigilated written exam; 15 min reading + 3 h writing; 4 questions / 100 marks; closed-book with PROVIDED formula sheet (Laplace table, Z-N & Tyreus-Luyben tuning, Padé, Routh arrays, Smith's-method chart); Casio FX82 only |
Routh stability limit, ultimate gain and Ziegler-Nichols PI tuning
- +1Form the characteristic equation 1 + G_OL = 0, i.e. (s+1)(s+2)(s+4) + Kc = 0 (the numerator gain of the process here is 1, so the loop gain is Kc).
- +1Expand the product to a polynomial: s^3 + 7 s^2 + 14 s + (8 + Kc) = 0.
- +1Write the first two Routh rows -- s^3: [1, 14]; s^2: [7, 8 + Kc].
- +1Compute the s^1 entry: b1 = (7*14 - 1*(8 + Kc)) / 7 = (90 - Kc) / 7.
- +1The s^0 entry is the last coefficient, 8 + Kc.
- +1For stability every first-column entry must be positive: (90 - Kc)/7 > 0 gives Kc < 90, and 8 + Kc > 0 gives Kc > -8, so -8 < Kc < 90.
- +1A physical controller gain is positive, so the binding limit is the ultimate gain Kcu = 90.
- +1At Kc = Kcu the s^2 row gives the auxiliary equation 7 s^2 + (8 + 90) = 7 s^2 + 98 = 0, so s^2 = -14 and the crossover frequency is omega_c = sqrt(14) = 3.74 rad/min.
- +1The ultimate period is Pu = 2*pi / omega_c = 2*pi / 3.74 = 1.68 min.
- +1Read the Ziegler-Nichols PI rule off the provided tuning sheet: Kc = 0.45*Kcu = 0.45*90 = 40.5 and TI = Pu/1.2 = 1.68/1.2 = 1.40 min.
Key terms
- Transfer function G(s)
- The ratio of output to input in deviation form in the Laplace domain, G(s) = Y-hat(s)/U-hat(s), derived with zero initial conditions; it captures how a process responds but carries no absolute-value information.
- Steady-state gain K
- How far the output ultimately moves per unit input, K = delta-y_ss/delta-u, in output-over-input units; its sign matters (K < 0 means the output falls when the input rises, e.g. a coolant valve).
- Time constant tau
- How fast a first-order process responds (units of time); a step response reaches 63.2% of its final change at t = tau, 95% at 3*tau and 99.3% at 5*tau.
- Deviation variable
- A variable measured from its steady-state value (y-hat = y - y-bar); transfer functions act only on deviations, so you subtract the steady state before transforming.
- Damping coefficient zeta
- The dimensionless shape of a second-order response: zeta > 1 over-damped, zeta = 1 critically damped, 0 < zeta < 1 under-damped (oscillates), zeta < 0 unstable.
- Dead time (time delay) theta
- A pure transport lag, G = e^(-theta*s); it adds unbounded phase lag (phi = -omega*theta) with an amplitude ratio of 1 (no attenuation), and is what makes a finite ultimate gain exist.
- FOPTD model
- First-order-plus-dead-time, G = K*e^(-theta*s)/(tau*s + 1) -- the standard low-order model fitted from a step-reaction curve (e.g. by the 1/3-2/3 method).
- Characteristic equation
- 1 + G_OL = 0, where G_OL is the product of all loop elements; its roots are the closed-loop poles, and the loop is stable only if they all lie in the left half-plane.
- Routh array / criterion
- A tabular test that decides whether every root of the characteristic polynomial has a negative real part -- and hence the loop is stable -- without solving the polynomial; it cannot handle dead time.
- Ultimate gain Kcu and period Pu
- The proportional-only gain that just sustains a constant-amplitude oscillation, and the period of that oscillation; both feed the Ziegler-Nichols and Tyreus-Luyben tuning rules.
- Gain margin and phase margin
- GM = 1/AR_OL(omega_c) and PM = 180 deg + phi_OL(omega_g): how much the loop gain can rise, and how much extra phase lag it can absorb, before instability (well-tuned targets GM ~ 1.7-4.0, PM ~ 30-45 deg).
- Relative Gain Array (RGA)
- Bristol's steady-state interaction measure for a multivariable plant; pair control loops on the relative gain that is positive and closest to 1, and avoid any negative relative gain.
- Cascade control
- An inner (secondary) loop on a fast intermediate variable nested inside an outer (primary) loop, so fast disturbances are rejected before they reach the primary variable; the inner loop must be faster than the outer.
- Feedforward control
- Measures a disturbance and acts before it upsets the output; the ideal feedforward controller is Gffc = -Gd/Gp, it does not affect closed-loop stability, and it is always paired with feedback trim.
CHEN90032 FAQ
Can AI help me study CHEN90032?
Yes. Sia is an AI tutor that explains Process Simulation and Control problems step by step -- deriving a dynamic model from a balance, building a Routh array, reading a Bode plot, or applying a Ziegler-Nichols tuning rule. It walks you through the reasoning and units rather than handing you an answer to submit, so you build the skill the closed-book exam tests.
Where can I find past exam papers or practice for CHEN90032?
The University of Melbourne Library keeps a past-exam-paper repository, and your Canvas/LMS subject site posts sample questions and worksheet solutions -- always the authoritative source to confirm. This guide adds re-authored, worked practice across the whole unit, and Sia can generate fresh practice questions and check your working line by line.
What can Sia do that a textbook can't?
A textbook is static; Sia is interactive. Paste your own step-test data, transfer function or block diagram and Sia adapts to it, explains the exact step you are stuck on, and catches a slipped sign, factor or unit before it costs you marks. It cannot guarantee a grade -- but it can make sure you understand why each step works.
Is CHEN90032 hard?
It is a quantitative subject: the difficulty is breadth, since you carry dynamics (balances, Laplace, transfer functions) into control (stability, Bode, tuning, multivariable) in one exam. Students who practise the derivations until they are automatic, and keep every sign and unit, generally find it manageable.
What is the hurdle in CHEN90032?
The 60% end-of-semester examination is a hurdle: you must pass the final exam to pass the subject, regardless of how well you did on the assignments and practicals. That makes exam technique the dominant thing to prepare -- confirm the exact hurdle wording on your Canvas subject site.
Is the CHEN90032 exam open or closed book, and what is examined?
It is effectively closed-book with a provided formula sheet (a Laplace-transform table, the Ziegler-Nichols and Tyreus-Luyben tuning rules, Pade approximants, Routh arrays and Smith's method chart) and a Casio FX82 calculator only. The paper is 4 questions over 100 marks spanning process dynamics and control -- transfer functions, block diagrams, stability, tuning and P&IDs. Confirm the format on Canvas.
What WAM do I need for a good grade in CHEN90032?
The University of Melbourne reports results as a WAM (Weighted Average Mark) and maps it to grade bands: H1 First-Class Honours (80-100), H2A (75-79), H2B (70-74), H3 (65-69) and Pass (50-64). In CHEN90032 your WAM is built from the four 10% continuous pieces (two assignments, two practicals) plus the 60% final exam -- and the exam is a hurdle, so a strong assignment record cannot lift you into H1 or H2A on its own if you do not pass the final. To target a band, work backwards: bank marks on the P&ID, lab reports and tuning working, then drill the exam question types where most of the weight sits. Sia helps you get there compliantly -- it explains each derivation and checks your working step by step so you understand the method, and it never guarantees a grade or does an assessed task for you.
How many points is CHEN90032 and what do I need to know first?
CHEN90032 is a 12.5-point subject, a Semester 1 graduate subject in the Melbourne Master of Engineering (Chemical). Melbourne does not publish a single prerequisite subject code here, so treat the entry as assumed knowledge rather than a named prerequisite -- confirm the exact requirements in the University Handbook and on the Canvas subject site. In practice it leans on undergraduate chemical-engineering fundamentals: mass and energy balances, calculus and ordinary differential equations, and comfort with Laplace transforms, since the subject turns balances into ODEs and ODEs into transfer functions from the first weeks. The subject is run through Canvas (the LMS), where the timetable, formula sheet and past-paper pointers live, and the study break before the exam -- SWOTVAC, the study week between the end of teaching and the exam period -- is your main window to consolidate before the June final.
How to study for the exam
Treat CHEN90032 as one chain and drill it end to end: a balance becomes an ODE, an ODE becomes a transfer function, and a transfer function becomes a tuned, stable loop. Spend the first weeks making the dynamics automatic -- deviation variables, the Laplace table, first-order K and tau, the second-order descriptors (overshoot, decay ratio, period) and the FOPTD fit -- because every control question is built on them. Then master the control toolkit as a sequence: the closed-loop transfer functions and characteristic equation, the Routh and Bode stability tests, the ultimate gain and period, and the Ziegler-Nichols and Tyreus-Luyben tuning rules, finishing with the advanced and multivariable structures (cascade, feedforward, direct synthesis, RGA and decoupling). Practise under the real constraints -- closed-book, a Casio FX82, and 1.8 minutes per mark -- always writing the method and carrying the sign and units, since the final is a hurdle you must pass and it awards working, not just the final number. Use SWOTVAC -- the study week between the end of teaching and the exam period -- for final revision: work full past exam papers and re-authored practice to time, closed-book with the provided formula sheet, so the method is automatic on the day. When a step will not click, ask Sia to explain it, then redo the problem from a blank page.
Your AI Engineering tutor for CHEN90032
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